/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the  "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id$
 */
package wx.xml.xalan.xpath.functions;

import wx.xml.xalan.xalan.res.XSLMessages;
import wx.xml.xalan.xalan.res.XSLTErrorResources;
import wx.xml.xalan.xml.dtm.DTM;
import wx.xml.xalan.xpath.XPathContext;
import wx.xml.xalan.xpath.axes.LocPathIterator;
import wx.xml.xalan.xpath.axes.PredicatedNodeTest;
import wx.xml.xalan.xpath.axes.SubContextList;
import wx.xml.xalan.xpath.objects.XNodeSet;
import wx.xml.xalan.xpath.objects.XObject;
import wx.xml.xalan.xpath.patterns.StepPattern;


/**
 * Execute the current() function.
 *
 * @xsl.usage advanced
 */
public class FuncCurrent extends Function {
    static final long serialVersionUID = 5715316804877715008L;

    /**
     * Execute the function.  The function must return
     * a valid object.
     *
     * @param xctxt The current execution context.
     * @return A valid XObject.
     * @throws javax.xml.transform.TransformerException
     */
    public XObject execute(XPathContext xctxt) throws javax.xml.transform.TransformerException {

        SubContextList subContextList = xctxt.getCurrentNodeList();
        int            currentNode    = DTM.NULL;

        if (null != subContextList) {
            if (subContextList instanceof PredicatedNodeTest) {
                LocPathIterator iter = ((PredicatedNodeTest) subContextList)
                    .getLocPathIterator();
                currentNode = iter.getCurrentContextNode();
            } else if (subContextList instanceof StepPattern) {
                throw new RuntimeException(XSLMessages.createMessage(
                    XSLTErrorResources.ER_PROCESSOR_ERROR, null));
            }
        } else {
            // not predicate => ContextNode == CurrentNode
            currentNode = xctxt.getContextNode();
        }
        return new XNodeSet(currentNode, xctxt.getDTMManager());
    }

    /**
     * No arguments to process, so this does nothing.
     */
    public void fixupVariables(java.util.Vector vars, int globalsSize) {
        // no-op
    }

}
